A high-performance electrocatalytic air cathode derived from aniline and iron for use in microbial fuel cells

Abstract

In this study, a high-performance electrocatalyst derived from aniline and iron was synthesized. The catalyst was prepared by pyrolyzing iron-impregnated polyaniline in an NH₃ atmosphere at high temperature. Pyrolyzing in NH₃ significantly increases the micropores, and the pyridinic nitrogen on the surface of the catalyst, leading to the excellent performance towards oxygen reduction. The electrocatalytic activity of this catalyst towards the oxygen reduction reaction was evaluated using a rotating ring disk electrode (RRDE). This catalyst exhibits a high onset potential of about 0.92 V (vs. reversible hydrogen electrode, RHE) and the half-wave potential difference between this catalyst and the benchmark Pt/C catalyst is only about 70 mV. The RRDE study also demonstrated that this catalyst for the four-electron reduction of oxygen has a very high selectivity. Applied as air cathodes in microbial fuel cells, the catalyst exhibits an excellent catalytic activity. The MFC with this catalyst achieves a maximum power density of 12.56 W m⁻³, higher than the 9.92 W m⁻³ of the MFC with a Pt/C catalyst and the 1.34 W m⁻³ of the MFC with bare graphite felt. These results demonstrate that this catalyst is an excellent alternative to the prohibitive Pt/C catalyst for practical applications.